This application claims the priority of German application 100 12 890.4, filed Mar. 16, 2000, the disclosure of which is expressly incorporated by reference herein.
The present invention relates to a multi-part vehicle wheel for a motor vehicle including hollow spokes arranged in a rim spider between air openings. A core made of metal foam remains in the rim spider and is precisely positionable in a casting die tool, and a ring surface, provided on the rim spider, radially projects beyond an interior-side or exterior-side wall of the rim spider for connection with a rim.
German Patent Document DE 197 54 959 A1 relates to a one-piece wheel for a motor vehicle which has hollow spokes and ring ducts and in which a respective remaining core of metal foam is arranged. This metal foam core is used instead of a removable sand core during casting of the wheel in a casting die tool.
It is an object of the invention to provide a multi-part wheel for a motor vehicle in which positioning of a metal foam core remaining in hollow spaces of the wheel is to be ensured and in which an optimal sealing-off of this metal foam core against outside influences when the vehicle wheel is assembled is achieved.
According to the invention, this object is achieved by providing the ring surface on the rim spider at an outer edge of the rim spider such that it defines a radially outward-extending first ring surface which is situated opposite a second ring surface in a spaced manner. The second ring surface includes either a bent or a straight ring web, and at least one of the first and second ring surfaces is connected by screwing devices with the rim.
Precise positioning of a metal foam core in a casting die tool is achieved according to the invention by needle pins forming positioning devices projecting from the core or arranged in a distributed manner. After casting of the wheel, these positioning devices are integrated, that is cast, into the wheel wall. In this case, the positioning devices are cast into the wall of the hollow spaces. The metal foam core can therefore no longer change its position in the hollow space, the wheel spoke, or in a ring space of the wheel.
Arrangement of the metal foam core in the casting die tool can also take place by way of a core portion extending out of the hollow spokes in the area of either the wheel center or the wheel center opening. Arrangement of the metal foam core in the casting die tool can also take place by way of a core portion extending out of the hollow spoke in the area of a wheel bolt bore. After casting of the wheel has been completed, and this core portion has been cut off corresponding to requirements, the wheel bolt bore and the central wheel opening will be interconnected.
A vehicle wheel, produced in this manner by way of a metal foam core, can be constructed in several pieces. The rim spider, for example, can be cast separately from the rim in the casting die tool. The rim can also be produced by a different method such as rolling.
In a first embodiment according to the invention, the rim spider is provided with approximately parallel extending edge-side ring surfaces, between which the hollow spokes and air openings are arranged. At least one of these ring surfaces is connected with the rim in a flat manner by way of screwing devices. The rim is correspondingly constructed with angular surfaces for this purpose. On a face side, the inner ring surface abuts a rim bottom surface and can be connected with the rim, for example, in a substance-adhering manner.
According to another embodiment of the invention, the inner ring surface has a bent ring web which is placed in a flat manner against the bottom surface of the rim. As a result, a second screw connection surface with respect to the rim is advantageously achieved. The first screw connection surface is obtained by way of the outer ring surface.
The metal foam core and the hollow space are protected against outside influences by a sealing strip or a sealing ring arranged between the connection surfaces of the rim spider and the rim. Thus, when the two wheel pieces, such as the rim and the rim spider, are connected, the sealing strip is held in a clamped-in manner.
When the hollow spoke is not filled with metal foam, in each embodiment of the wheel, a sealing strip can also be interposed so that the hollow space is protected against outside influences.
Instead of having the opening, the hollow spoke can also be closed off by way of a wall which will then be supported on the bottom surface of the rim.